Vehicles (e.g., manned aircraft and unmanned aerial vehicles (UAVs)) operating in low visibility conditions often require navigation and guidance information. For example, manned aircraft taking off in low visibility conditions (below 600 foot (ft.) runway visual range (RVR)) often require a Category II or III instrument landing system (ILS) at the airport. The Cat II and III ILS are ground infrastructure equipment which are very expensive to install and maintain. Only 80-90 airports in the US have this equipment. Thus, when conditions below 600 ft. RVR occur at the vast majority of regional airports where Cat II or III equipment are not available, the number of aircraft that can takeoff from those airports is drastically reduced to zero which creates a domino delay effect, as all subsequent flights of the affected aircraft scheduled for the next several hours or the remainder of the day are canceled or delayed.
U.S. Pat. No. 8,849,481, entitled “GPS Carrier-phase Based Relative Navigation,” incorporated herein by reference in its entirety and assigned to the assignee of the present application discusses the use of GPS carrier phase relative navigation to provide guidance for unmanned aircraft takeoff.
RTCA, Incorporated has published document DO-229D which contains minimum operational performance standards (MOPS) for aircraft navigational equipment (2D and 3D) using the Global Positioning System (GPS).
The aviation industry is in the process of developing performance requirements to use an Enhanced Flight Vision System (EFVS) as a visual aid to the flight crew for taxi from the gate to the runway where take-off is contemplated. The performance requirements will also include the integrity requirements for using the EFVS for take-off, as well. The integrity requirements to support take-off with an EFVS will likely be 2 to 3 orders of magnitude higher than the taxi requirements. It is not possible for a single EFVS to meet the higher integrity requirements. To meet the integrity requirements for take-off high integrity guidance and navigation system as described herein can be used to augment and/or monitor the EFVS image positioning by becoming the image positioning system for a synthetic image representing the take-off runway and its center line. The synthetic image may be over laid on or combined with the EFVS image to allow the flight crew to compare both images full time thereby validating both images agree and can then be used to support take-off in low visibility.